Mepolizumab

NUCALA

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Pronunciation: me-poe-LIZ-yoo-mab (nyoo-KAH-la)

Mepolizumab ballicule: receptor binding, kinetics and half-life diagram — Mechanism of action: Mepolizumab ballicule

What it isMonoclonal antibody neutralizing IL-5; severe eosinophilic asthma, eosinophilic COPD, EGPA, hypereosinophilic syndrome, and chronic rhinosinusitis with nasal polyps.

Why this oneUnlike benralizumab, it neutralizes the IL-5 ligand rather than directly depleting eosinophils through the receptor.

What limits itIt is not rescue therapy and benefit depends on an eosinophilic phenotype. Hypersensitivity and herpes zoster can interrupt use; vaccinate before starting.

Mepolizumab molecular structure (skeletal formula) — Molecular structure: Mepolizumab

FDA label

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FDA dosing	Population	Start	Target	Max
Severe asthma with eosinophilic phenotype	Adults & peds ≥12 y	100 mg SC q4wk	100 mg SC q4wk	100 mg SC q4wk
Severe asthma with eosinophilic phenotype	Peds 6–11 y	40 mg SC q4wk	40 mg SC q4wk	40 mg SC q4wk
Chronic rhinosinusitis with nasal polyps (CRSwNP)	Adults ≥18 y	100 mg SC q4wk	100 mg SC q4wk	100 mg SC q4wk
COPD with eosinophilic phenotype	Adults	100 mg SC q4wk	100 mg SC q4wk	100 mg SC q4wk
Eosinophilic granulomatosis with polyangiitis (EGPA)	Adults	300 mg SC q4wk	300 mg SC q4wk	300 mg SC q4wk
Hypereosinophilic syndrome (HES)	Adults & peds ≥12 y	300 mg SC q4wk	300 mg SC q4wk	300 mg SC q4wk

Renal No dose adjustment; not cleared renally

Hepatic No dose adjustment expected (degraded by proteolytic enzymes)

Instructions

SC injection into upper arm, thigh, or abdomen
300 mg given as 3 separate 100 mg injections ≥5 cm apart
Reconstitute lyophilized vial with 1.2 mL Sterile Water; do not shake
If dose missed, give as soon as possible then resume usual schedule

Available strengths

inj 100 mg/mL

Cautions

Hypersensitivity reactions (anaphylaxis, angioedema, bronchospasm, hypotension, urticaria, rash) — discontinue if they occur
Not for acute bronchospasm or status asthmaticus
Herpes zoster infections — consider vaccination
Do not stop corticosteroids abruptly on initiation; taper gradually
Treat pre-existing helminth infections before therapy

Adverse reactions

Headache
Injection site reaction
Back pain
Fatigue
Oropharyngeal pain
Arthralgia (CRSwNP)
Diarrhea, cough (COPD)

Pregnancy Insufficient data; monoclonal antibody crosses placenta (greater transfer in 2nd/3rd trimester); no fetal harm in monkeys at ~9x MRHD

Lactation No human milk data; IgG present in milk in small amounts; weigh benefits vs. risk

Cost

Mepolizumab (NUCALA)

Strength		#/mo	generic $/unit	CostPlus
100 mg/mL	inj	per unit		not offered

NADAC is a voluntary CMS survey of what retail community pharmacies pay for the drugs they stock. Mepolizumab is administered under clinical supervision and dispensed outside retail pharmacies, so it rarely appears on surveyed invoices.

NO BOXED WARNINGS

Principal riskHypersensitivity reactions; not a rescue for acute asthma; herpes zoster

Classes and tags

Clinical profile

Therapeutic safety burden1 / 4

Overdose danger0 / 4

Weight-gain liability0 / 4

Sedation liability0 / 4

QT / Torsades0 / 4

Direct muscarinic antagonism0 / 4

Legacy pregnancy categoryN/A (post-2015 labeling)

Defining liabilityHypersensitivity reactions and herpes zoster

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